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Development of the aorta Development of the aorta takes place during the third week of gestation. It is a complex process associated with the formation of the endocardial tube (heart tube) at day 21. blood islands appear bilaterally in the splanchnic mesoderm parallel and close to the midline of the embryo forming a pair of longitudinal vessels, the Dorsal Aortae. The two ventral aortae fuse to form the aortic sac which is continuous with truncus arteriosus. The dorsal aortae fuse to form the midline descending aorta. Six paired aortic arches, the so-called branchial arch arteries, develop between the ventral (aortic sac) and dorsal aortae. In addition, the dorsal aorta gives off several intersegmental arteries
Establishment of Cardiogenic field (Langman’s Medical Embryology)
YolkSac
(Langman’s Medical Embryology)
Aortic Sac
Dorsal Aorta
Heart
Intersegmental branches
3rd branchial arch Gives rise to internal Carotid artery
Dorsal Aorta
Lt Rt
truncus arteriosus
the midline descending aorta
Truncus Arteriosus
Internal carotid artery
Common Carotid artery
Rt subclavvian art
Aortic sac
Lt Rt
Brachiocephalic Trunk
Ascending aorta
The aortic sac gives rise to Ascending aorta and brachiocephalic trunk
Dorsal aorta
Ductus arteriosus
Right pulmonary artery
Internal carotid art
Ventral Aorta
Pulmonary Trunk
Common carotid art
The vessels derived from each arch are as follows: 1st pair: contributes to formation of the maxillary and external carotid arteries. 2nd pair: contributes to formation of the stapedial arteries of the ear 3rd aortic arch constitutes the commencement of the internal carotid artery and common carotid arteries, therefore it is named as the carotid arch.
Internal carotid artery
Common carotid artery
Rt Lt External carotid
art
4th arch: The left arch forms the segment of normal left aortic arch between the left common carotid and subclavian arteries. The right fourth arch forms the proximal right subclavian artery. The distal right subclavian artery is derived from a portion of the right dorsal aorta and the right seventh intersegmental artery. The rest of the right aorta degenerates 5th arch degenerate vessels
Intersegmental arteries
Lt Rt
3 4
5 4 4
Dorsal aorta
Degenerated Rt dorsal aorta
Aortic arch
Right subclavian artery
6th pair: The left arch contributes to the formation of the main and left pulmonary arteries and ductus arteriosus; this duct obliterates a few days after birth. The right sixth arch contributes to formation of the right pulmonary artery. Rt Lt
Dorsal Aorta
Ventral Aorta
the seventh intersegmental arteries enlarge and migrate cranialy to form the distal subclavian arteries. The left subclavian artery is derived entirely from the left seventh intersegmental artery, whereas the portions of the right are derived from the right fourth arch and the right dorsal aorta.
Right subclavian artery
Right Left
Vertebral Artery is formed by seven intersegmental arteries
Vertebral Artery
Posterior intercostal arteries
Internal thoracic artery
3
4
5
Connection of int. carot with dorsal aorta degenerate
Internal carotid artery
Subclavian artery
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